ABSTRACT
This chapter presents in detail some of the more commonly used microbial toxicity screening procedures. There are two main groups of toxicity screening tests: in vitro “health effect” tests and “ecological effect” tests. “Health effect” toxicity tests are based on the use of subcellular components, isolated cells, tissue sections, or isolated whole organs. “Ecological effect” tests are conducted to measure mainly the acute toxicity of chemicals to aquatic organisms representing various trophic levels of the food chain. Since enzymes drive numerous key metabolic reactions in microbial, plant, and animal cells, their inhibition could be the underlying cause of toxicity to the cells. Bioluminescent or luminous bacteria are mostly marine microorganisms which live freely in ocean water or in association with higher marine organisms. Bacterial assays for chemical toxicity in aquatic environments are based on measurement of growth inhibition, respiration, or viability of the cells. In principle, the measurement of the heat flux in the presence of inhibitors can provide a basis for evaluating inhibitory effects and the “microtoxicity” of contaminants.
